Field of the Disclosure
This application relates to the field of rock grinding or comminution mills in which a liner includes lifters for distributing the contained material.
Background Art
For many industrial purposes it is necessary to reduce the size of rocks to a much smaller particle size (commonly called “comminution”). For example, the larger rocks may be blasted out of an area such as a hillside, pit or mine, and these larger rocks (sometimes the size of boulders) are then directed into a large rock crusher, which is often the first stage of comminution after blasting. The blasted rock sizes can exceed 1000 mm (>40 inches) in size. The resulting output of the crusher is typically smaller rock that is less than 200 mm (8 inches) in a longest dimension which is then fed to a grinding mill. The grinding mill typically comminutes the crushed rock below 50 mm (2 inches) sized rocks or less.
One known grinding mill comprises a large cylindrical grinding section, rotating along its horizontal axis, which often could have a diameter of as much as ten to forty feet. One such mill is described in U.S. Pat. No. 7,497,395 incorporated herein by reference. The material (rocks), along with water, and/or air, is directed into one end of the continuously rotating grinding section, which comprises various types of lifting ribs positioned axially on the inside surface of the grinding section to carry the rocks upwardly, on its surface, in a curved upwardly directed path within the grinding chamber so that these partially ground rocks tumble (fall) back onto other rocks in the lower part of the chamber (see FIG. 9). Thus, these rocks impact each other and the inner surface of the grinding mill, and are thus fragmented (broken up) into smaller rock fragments. Also, sometimes large iron balls (e.g., two to six inches in diameter) are placed in the grinding chamber to obtain improved results.
It often takes a tremendous amount of power to operate such grinding mills, and also there are other substantial costs involved. There are a number of factors which relate to the effectiveness and the economy of the operation, and the embodiments of the disclosure are directed toward improvements in such mills and the methods employed.